Contour Enthusiasts Group Archives Forums General Troubleshooting V6 Surging with A/C on

Well, it's our first sunny warm (60 deg F) day up here in sunny Toronto Canada so I put the air-conditioning on on my '98 Mystique V6.

In idle, the RPM's cyscled every minute or so from 600 to 1000. In motion, there was definite surging, even when the RPM's were at 2000.

Is this normal for this car. I can understand if the compressor was cycling in and out due to a low outside temperature, but this is just like it runs when the defrost is on.

Isn't the compressor meant to run all the time in A/C mode? Is there a fix, because the car feels uncontrollable in slow traffic.

1998 Mystique, v6 Duratec, Sports Package, AT

It's unfortunately normal on SVT's, non-SVT's to a lesser extent. The compressor is supposed to cycle on and off when in A/C or Def mode. Related to the way the PCM controls the operation of the IAC valve.

Of course, if you get a check engine light or this is the first time it's ever happened, it could be something else.

The compressor surge on the Contour is the worst I've ever experienced--much worse than on the GM cars (Saturn/Fiero/Beretta) we've had in the past. I had my '00 Contour checked by the dealer when it was new because I thought something was wrong, and they said "they all do that." And they do....

If the PCM is telling IAC valve to open up and set the RPMs higher when the A/C turns on, can I:

Set my a/c compressor somehow to run full time when it is on? Or,

Use the "throttle hang" fix to reduce the IAC's effect on my RPMs when the compressor kicks in?

BTW, I bought the car in the fall, this is the first bit of driving with the A/C on.

Any help is appreciated

So they all do that, Big business and their greedy cost cutting in the last few years is what really did it. RIGHT "Visteon" employees?????
Paul
My brothers 98 F-150 4.6 V-8 does it! It's the nature of the beast.

My apologies to the Visteon folks, my poor wording or lack of finishing the sentence.
How do I say this, Visteon was only doing what Ford (starting with the CEO & down) asked. Cut costs or else. When Visteon designs & engineers a good working system Ford's bean counters still jumped in, "too much $, cut some more & more & more."
There's a company in my area that makes sensors & controls for the big three and being a friend of the owner, that's the gist of his comments. He had to tell Chrysler he would no longer supply an particular part, "if he cut the cost anymore it won't function or have a high failure rate. A few weeks later they came back and excepted his price. One on else could even come close to his price that Chrysler wanted cut.
All about the bottom line not about giving the customer a good product.
Again my apologies to the suppliers out there.
Paul


[This message has been edited by F111D F (edited April 05, 2001).]

The IAC valve is from Hitachi, it's Ford logic and a Ford engineer calibrated the idle system. You are mentioning Visteon why????

That's cool, Paul. You are correct, and to be honest, I'm sure Visteon does this same stuff to a small degree to the Tier 2s and 3s out there when the order comes down from Ford, but not nearly so much. And in this case, as I said, the key pieces of idle quality are not in our hands.

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Rob Weiss
'99 Mystique, 2.5L, MTX, Black/Tan, 27K miles
Build Date: December 14, 1998

[This message has been edited by Rob Weiss (edited April 05, 2001).]

My 96 2.5 idles rather smoothly with a/c on (and it is on all the time here in Tampa) with no noticeable surge. I do notice a vibration, however.

My SE surges also, more noticable in lower gears. It is normal, especially on smaller displacement vehicles. My '91 Escort did it, my '96 Escort did it. My '98 Ranger XLT 4.0L V-6 4x4 did not.

I have no problems with my car surging. When I switch on the A/C there is no change, even the air temp stays the same...

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RWheels
95LX 2.5MTX
Modless

My main reason for concern is that the 2.5 Duratec in my MPV doesn't do this at all.

Oh well, it's off to the dealer on ednesday for its last on-warranty check up.